The present invention relates to a spring connector.
FIG. 12 shows an example of the structure of a related-art spring connector. FIG. 12 is a longitudinal sectional view showing an example of the related-art spring connector. In FIG. 12, a coiled spring 12 is inserted in the cylindrical portion of a tube 10 formed of a conductive material which has the tip side to be an opened cylinder and the base end side to be a terminal having a small diameter, and furthermore, a pin 14 formed of a conductive material in which the tip side is stepped to have a small diameter is inserted therein and the open end of the tube 10 is caulked such that the pin 14 can be freely protruded and retracted while not being slipped out. The base end face of the pin 14 is a slant face. An assembly of the tube 10, the coiled spring 12 and the pin 14 is pressed and fixed into a holder 16 formed of an insulating resin from the tip side of the holder 16. The tube 10 and the pin 14 are plated with gold to be a good conductive material.
Moreover, FIG. 13 shows another example of the structure of the related-art spring connector. FIG. 13 is a longitudinal sectional view showing an example of the related-art spring connector of a right angle type. In FIG. 13, a coiled spring 12 and a pin 14 are inserted in the cylindrical portion of a tube 10 and an opening end is caulked so that the pin 14 can be freely protruded and retracted while not being slipped out in the same manner as in the example of FIG. 12. There is a difference in that a bulged portion is formed on the base end side of the tube 10 and the tube 10 is pressed into a holder 16 from the base end side so that the bulged portion and the base end face of the holder 16 are caused to interpose a terminal 18 therebetween. Furthermore, the side face of the holder 16 is formed to abut on a substrate 20 and the terminal 18 is properly bent along the substrate 20 and can be electrically connected to the wiring terminal of the substrate 20 by soldering.
Also in both of the spring connectors shown in FIGS. 12 and 13, the pin 14 abuts on the inner peripheral face of the cylindrical portion of the tube 10 to form a conductive circuit. In order to reduce an electric resistance caused by the abutment, the pin 14 and the tube 10 are plated with gold. However, the inner cylindrical portion of the tube 10 is a blind hole having one end opened, and a plating solution and a cleaning solution neither sufficiently flow into and out of the inner part of the hole so that plating failures are apt to be caused. Consequently, there is a drawback that conducting failures are apt to be caused. Moreover, there is a drawback that the tube 10 is formed by cutting, resulting in an increase in a manufacturing cost. In the right angle type shown in FIG. 13, furthermore, the terminal 18 is added to be a part so that the manufacturing cost is increased correspondingly. In addition, there is a possibility that the resistance of a whole conductive path might be increased due to electrical conduction caused by the contact of the tube 10 with the terminal 18.
It is therefore an object of the present invention to provide a spring connector provided with high reliability and can be manufactured inexpensively.
In order to achieve the above object, according to the present invention, there is provided a spring connector, comprising:
an insulating holder, having a first face and a second face, the insulating holder formed with a first hole having a first diameter at the first face, and a second hole having a second diameter larger than the first diameter and extended from the second face so as to communicate with the first hole;
a plate-shaped conductive terminal, having a base portion, at least one pair of guide portions extended from the base portion so as to define a concave portion therebetween, the terminal fitted into the second hole such that the concave portion faces the first hole;
a conductive pin, including a plunger portion having a diameter smaller than the second diameter and a base portion having a diameter substantially identical with the second diameter, the base portion of the pin being fitted with the guide portions so as to be slidable along the concave portion; and
a spring member, provided in the concave portion so as to urge the pin toward the first face of the holder, so that the plunger portion of the pin is retractably protruded from the first face of the holder through the first hole.
In this configuration, since the plate-shaped terminal which can be manufactured by the pressing is used in place of the tube manufactured by cutting as described with reference the related-art art, manufacture can be carried out inexpensively.
In a case where a plurality of concave portions are formed in a single terminal, a plurality of conductive pins are provided to constitute a spring connector having a large number of contacts. Therefore, the manufacture can be carried out more inexpensively as compared with the related-art case in which a plurality of spring connectors are arranged.
Preferably, the terminal and the pin are plated with gold.
Even in this configuration, a plating solution and a cleaning solution can easily flow into and out of a portion in which the pin and the terminal slidably fitted with each other. Consequently, plating can easily be carried out so that the reliability of an electrical connection can be enhanced.
Preferably, a tongue piece portion is extended from the base portion of the terminal so as to be protruded from the second face of the holder.
This configuration is suitable for a spring connector in which a terminal is inserted in a hole provided on a substrate and is electrically connected to a circuit provided on the back surface of a substrate by soldering.
Here, it is preferable that a side face which is other than the first face and the second face of the holder faces a substrate on which a circuit is provided. The tongue piece portion is so bent as to extend along the substrate.
This configuration is suitable for a spring connector in which a terminal is electrically connected to a circuit provided on an obviate surface of a substrate, on which the holder is placed, by soldering.
Here, it is preferable that the tongue piece portion is so bent as to extend toward the first face of the holder. The holder is formed with a recess to which a tip end of the tongue piece portion is inserted so as to prevent the tongue piece portion from deforming in a direction that the holder is away from the substrate according to a retracting movement of the pin.
In this configuration, the tongue piece portion can be provided in the installation area of the holder so that a mounting area can be reduced correspondingly. Moreover, the tip portion of the tongue piece portion is engaged with the recess of the holder. Therefore, as long as the tongue piece portion is fixed to the surface of the substrate, the holder is not separated from the substrate.
Alternatively, the tongue piece portion is so bent as to elastically contact with the substrate.
This configuration is suitable for a spring connector in which a terminal is elastically come in contact with a circuit provided on the obviate surface of the substrate, thereby carrying out an electrical connection of the terminal. Consequently, it is possible to omit a connecting work by soldering.
Preferably, the first face and the second face of the holder extend in a first direction. The second hole obliquely extends with respect to a second direction perpendicular to the first direction.
In this configuration, when the plunger portion of the pin is abutted on an inspected pad and furthermore they are approached with each other, a rubbing operation is carried out between the plunger portion and the inspected pad so that reliable conduction therebetween can be attained. In addition, the force for pressing the pin against the terminal is applied so that the conductivity can be enhanced.
In order to attain the above advantage, according to the present invention, there is also provided a conductivity inspection method, comprising the steps of:
providing the spring connector as set forth in claim 1;
providing a conductive pad on which the plunger portion of the spring connector is abutted to inspect that the conductive pad and the spring connector is electrically connected; and
determining an extending direction of the second hole of the holder so as to be oblique with respect to a direction in which the conductive pad extends.